
package org.boris.expr.function.excel;

import org.boris.expr.Expr;
import org.boris.expr.ExprDouble;
import org.boris.expr.ExprException;
import org.boris.expr.IEvaluationContext;
import org.boris.expr.function.AbstractFunction;

public class CRC32 extends AbstractFunction
{

	public Expr evaluate( IEvaluationContext context, Expr[] args )
			throws ExprException
	{
		assertArgCount( args, 1 );
		String string = asString( context, args[0], false );
		return new ExprDouble( Long.parseLong( getCRC32( string ), 16 ) );
	}

	public static String getCRC32( String str )
	{
		int[] table = {
				0x00000000,
				0x77073096,
				0xee0e612c,
				0x990951ba,
				0x076dc419,
				0x706af48f,
				0xe963a535,
				0x9e6495a3,
				0x0edb8832,
				0x79dcb8a4,
				0xe0d5e91e,
				0x97d2d988,
				0x09b64c2b,
				0x7eb17cbd,
				0xe7b82d07,
				0x90bf1d91,
				0x1db71064,
				0x6ab020f2,
				0xf3b97148,
				0x84be41de,
				0x1adad47d,
				0x6ddde4eb,
				0xf4d4b551,
				0x83d385c7,
				0x136c9856,
				0x646ba8c0,
				0xfd62f97a,
				0x8a65c9ec,
				0x14015c4f,
				0x63066cd9,
				0xfa0f3d63,
				0x8d080df5,
				0x3b6e20c8,
				0x4c69105e,
				0xd56041e4,
				0xa2677172,
				0x3c03e4d1,
				0x4b04d447,
				0xd20d85fd,
				0xa50ab56b,
				0x35b5a8fa,
				0x42b2986c,
				0xdbbbc9d6,
				0xacbcf940,
				0x32d86ce3,
				0x45df5c75,
				0xdcd60dcf,
				0xabd13d59,
				0x26d930ac,
				0x51de003a,
				0xc8d75180,
				0xbfd06116,
				0x21b4f4b5,
				0x56b3c423,
				0xcfba9599,
				0xb8bda50f,
				0x2802b89e,
				0x5f058808,
				0xc60cd9b2,
				0xb10be924,
				0x2f6f7c87,
				0x58684c11,
				0xc1611dab,
				0xb6662d3d,
				0x76dc4190,
				0x01db7106,
				0x98d220bc,
				0xefd5102a,
				0x71b18589,
				0x06b6b51f,
				0x9fbfe4a5,
				0xe8b8d433,
				0x7807c9a2,
				0x0f00f934,
				0x9609a88e,
				0xe10e9818,
				0x7f6a0dbb,
				0x086d3d2d,
				0x91646c97,
				0xe6635c01,
				0x6b6b51f4,
				0x1c6c6162,
				0x856530d8,
				0xf262004e,
				0x6c0695ed,
				0x1b01a57b,
				0x8208f4c1,
				0xf50fc457,
				0x65b0d9c6,
				0x12b7e950,
				0x8bbeb8ea,
				0xfcb9887c,
				0x62dd1ddf,
				0x15da2d49,
				0x8cd37cf3,
				0xfbd44c65,
				0x4db26158,
				0x3ab551ce,
				0xa3bc0074,
				0xd4bb30e2,
				0x4adfa541,
				0x3dd895d7,
				0xa4d1c46d,
				0xd3d6f4fb,
				0x4369e96a,
				0x346ed9fc,
				0xad678846,
				0xda60b8d0,
				0x44042d73,
				0x33031de5,
				0xaa0a4c5f,
				0xdd0d7cc9,
				0x5005713c,
				0x270241aa,
				0xbe0b1010,
				0xc90c2086,
				0x5768b525,
				0x206f85b3,
				0xb966d409,
				0xce61e49f,
				0x5edef90e,
				0x29d9c998,
				0xb0d09822,
				0xc7d7a8b4,
				0x59b33d17,
				0x2eb40d81,
				0xb7bd5c3b,
				0xc0ba6cad,
				0xedb88320,
				0x9abfb3b6,
				0x03b6e20c,
				0x74b1d29a,
				0xead54739,
				0x9dd277af,
				0x04db2615,
				0x73dc1683,
				0xe3630b12,
				0x94643b84,
				0x0d6d6a3e,
				0x7a6a5aa8,
				0xe40ecf0b,
				0x9309ff9d,
				0x0a00ae27,
				0x7d079eb1,
				0xf00f9344,
				0x8708a3d2,
				0x1e01f268,
				0x6906c2fe,
				0xf762575d,
				0x806567cb,
				0x196c3671,
				0x6e6b06e7,
				0xfed41b76,
				0x89d32be0,
				0x10da7a5a,
				0x67dd4acc,
				0xf9b9df6f,
				0x8ebeeff9,
				0x17b7be43,
				0x60b08ed5,
				0xd6d6a3e8,
				0xa1d1937e,
				0x38d8c2c4,
				0x4fdff252,
				0xd1bb67f1,
				0xa6bc5767,
				0x3fb506dd,
				0x48b2364b,
				0xd80d2bda,
				0xaf0a1b4c,
				0x36034af6,
				0x41047a60,
				0xdf60efc3,
				0xa867df55,
				0x316e8eef,
				0x4669be79,
				0xcb61b38c,
				0xbc66831a,
				0x256fd2a0,
				0x5268e236,
				0xcc0c7795,
				0xbb0b4703,
				0x220216b9,
				0x5505262f,
				0xc5ba3bbe,
				0xb2bd0b28,
				0x2bb45a92,
				0x5cb36a04,
				0xc2d7ffa7,
				0xb5d0cf31,
				0x2cd99e8b,
				0x5bdeae1d,
				0x9b64c2b0,
				0xec63f226,
				0x756aa39c,
				0x026d930a,
				0x9c0906a9,
				0xeb0e363f,
				0x72076785,
				0x05005713,
				0x95bf4a82,
				0xe2b87a14,
				0x7bb12bae,
				0x0cb61b38,
				0x92d28e9b,
				0xe5d5be0d,
				0x7cdcefb7,
				0x0bdbdf21,
				0x86d3d2d4,
				0xf1d4e242,
				0x68ddb3f8,
				0x1fda836e,
				0x81be16cd,
				0xf6b9265b,
				0x6fb077e1,
				0x18b74777,
				0x88085ae6,
				0xff0f6a70,
				0x66063bca,
				0x11010b5c,
				0x8f659eff,
				0xf862ae69,
				0x616bffd3,
				0x166ccf45,
				0xa00ae278,
				0xd70dd2ee,
				0x4e048354,
				0x3903b3c2,
				0xa7672661,
				0xd06016f7,
				0x4969474d,
				0x3e6e77db,
				0xaed16a4a,
				0xd9d65adc,
				0x40df0b66,
				0x37d83bf0,
				0xa9bcae53,
				0xdebb9ec5,
				0x47b2cf7f,
				0x30b5ffe9,
				0xbdbdf21c,
				0xcabac28a,
				0x53b39330,
				0x24b4a3a6,
				0xbad03605,
				0xcdd70693,
				0x54de5729,
				0x23d967bf,
				0xb3667a2e,
				0xc4614ab8,
				0x5d681b02,
				0x2a6f2b94,
				0xb40bbe37,
				0xc30c8ea1,
				0x5a05df1b,
				0x2d02ef8d,
		};
		byte[] bytes = str.getBytes( );
		int crc = 0xffffffff;
		for ( byte b : bytes )
		{
			crc = ( crc >>> 8 ^ table[( crc ^ b ) & 0xff] );
		}
		crc = crc ^ 0xffffffff;
		return Integer.toHexString( crc );
	}

}
